根据《SDH长途光缆传输系统工程验收规范》,系统试运时间为(),试运行结束,建设单位应提交试运行报告,并准备终验。
A.1个月
B.6个月
C.3个月
D.10个月
参考答案:C
—Your Chinese is so beautiful. How long have you studied it?
—I have studied it _____ 2008. [ ]
A. since
B. before
C. for
D. till
量制、量纲的含义及区别